Method of producing solid mixed chlorides of magnesium and calcium in divided form



Patented Mar. 1932.

unite; stares PA E T mm sHELDo n HEATH; on MIDLAND, MICHIGAN, SSIGNoR'aO rHE DO CHEMICAL COIVL Perry, on MIDLAND; MICHIGAN, aconrone'rron OFYVMICHIGAN I The present invention is, concerned with the production of fmixed chlorides of mag;

' METHODOF rnonuome somn MI'XED' CHLORIDES orivmennsrulvrnnn CALCIUM I IN DIVIDE D FORM a 1 No Drawing.

- nesium and'calcium inldivided form,particu larlyin the'form of flakes made by chilling,

a solution of said chloridesupon a cooled surdrum dipping in, a concentrated solution of.

' solidification is suchthat a satisfactory rate face and removing the solidified chlorid therefrom.

Calcium chloride maybe readily fialzed upon an internally water cooled 'revolvlng said chloride; a thin coating of the solid chloride being formed on the surface of the drum which may be scraped therefromwith asuitable knife or scraper to form a flaked product. In this case the :temperature of of working may be experiencedat allfseasons of the year with' avaliable naturalrooling waters. Then, however, it is attempte'd'to proceed in thejsamef manner with a mixed solution contalning magnesium and calc um chlorides, it is found that the temperature of solidification "willvin many cases be too lowjto permit solidification by the use of natural asl cooling waters at all seasons, or will slow down the rate of working to a disadvantageous degree; I am not aware that magnesium l 'chloride-calcium chloride solutionshave been successfullyfiaked heretofore, or that a flaked mixed chloride has beenjmade. o I

5 I have discovereda method by which' the temperature of 'solidification of such mixed solutions may be raised to such-an extent that flaking may be practiced successfully-and l cheaplyiin a somewhat similar manner to the flaking of straight calcium'chloride, p

I To the accomplishment of the foregoing andrelated'ends, the invention; then, consists r of the method hereinafter fully described and particularly' 'pointedout in the claims, they following description setting forth in I detail several modes of procedure embodyingmy invention, such'fdisclosed modes constituting,

, however; but several of thevarious ways m: which the principle of the invention may be 7 used. i v

' Startingiwitha parent solution havingany compositionratio ofcalc'ium. chloridemagp I nesiumchloride-water, my in'ethod'of ,produc temperature of themother liquors will'be V inga flake material all of it or a portfion;

. Application fiieanovembei @1928. sem No. 317,495. 7

thereof may be practiced as follows, to"

Concentrate the parentsolution to its saturated'atmosphericboiling point and continue concentration at its atmospheric boilingv'point with salting out of the crystals" and 'witl'lrise ofboi'ling temperature until the temperature 'of solidification of the mixture or slurry of crystals and concentrated mother liquoris raised sufficiently to leavea suitable heat head above cooling agent temperature If '5 the resulting slurry, before reaching such solidification temperature, is toothick to pump or otherwise handle'to' the flaking stepyit will be necessarytoseparate a suflicient portion of the crystals from the'slurry to keep it of a handling consistency when such 7 proper point is reached. Any soderived mother liquorwhichhas a solidification temperature 7 well aboveithe' temperature of the available cooling agent may be flaked. on the ordinary '70 typelfof fiaker heretofore used for straight r I 051612? Q Q ose parent solutions inwhich theratlo I m -V o CaCl is I either" high, low the slurry readily flaked Without elimination a of partof the crystallized saltsq i p It is possible in most cases to flakeall of the parent concentrated solution without sep-:

aration-ofjapart o'fflit as hydrated crystals, 7 although slurries derived from tions in which the ratio is within a certain intermediateqrange will have a solidification temperature requiring either super-cooling or areduced rate of flaking, if using natural coolingfmeans. Those parent solutions'which may have the temperature of solidificationso raised with- I .out the necessity of removing a portion of the 2.. I

parent solu- I crystal slurry too thick to pump results.

pheric from the standpoint of obtaining a high freezing point motherliquor befoge a a 1'0- ceeding in the latter way, however, the flaking of the slurry is more diflicult at atmospheric pressure, since flash evaporation occurs upon release of the slurry to atmospheric pressure, causing it to cool and become thick. In some cases where nearly pure MgCl or caCl isproduced the concentration to form a slurry may be done under low vacuum and a flakable slurry obtained. However, all thlngs considered, working at atmospheric pressure is preferable when flaking is to be done.

If, however, the mixed chlorides are to be granulated by other means and self evaporation of water from the surface layers of the particles is to be secured, then the concentration to a slurry under pressure permits mixed chlorides of intermediate ratios to be more easily produced.

With parent solutions having a composition ratio corresponding to tachydrite; crystal composition (CaCLQMgChJQILO), no change in the composition ratio of the mother liquor may be expected to occur by concentration at atmospheric pressure. The same limitation applies to. a parent solution having a -MgCl ,1the other. high inCaCl and each composition ratio Ma k 29 C8012 Concentration of such a solution at atmos- =pheric pressureresults in salting out mixed double' hydrated salts without auteration of mother liquor composition.

The'chloride content of the product may,

however. be raised :by producing a slurry of hydrated salt crystals and mother liquor in all cases, and thechoice of the method of solidification and division of the resulting solid chlorides will depend upon the tempera ture of solidification and the mechanical handling characteristics of" the slurry so obtained.

- tion ratio. r less than In order to work up mixed chloride solutions-of all ratios-into flaked products comprising mixed solid chlorides, the following procedures may be followed.

With parent solutions having a composi- (molecular and not directly flalmble as derived is torbe flaked. Itis preferable to concentrate at pressures greater thanatmos as described above for such solution. The recycledfmother liquor will be built up to a concentration permitting deflection to the slurry, the preferred procedure will be to first concentrate said solution at reduced pressure to salt out tachydrite crystals. Such tachydrite will then be separated from the mother liquor and washed to remove a portion of the CaCl and leave a mass of crystals having a composition ratio sufficiently high in MgCl to permit flaking when converted into a slurry ing will be recycled through the reduced pressure concentrating step to build up a mot-her liquor .composition permitting deflecting same to the slurry flaking procedure, said mother liquor having preferably a composition high in CaCl e. g. 6 to 10 parts MgCl to parts 'CaCl lVith parent solutions having a: composition ratio reater than 21 and not di- CaCl g 1 rectly flakable as a derived slurry, a preferred procedure will be to concentrate at reduced pressure to salt out tachydritc crystals, recycling the mother liquor and separating the tachydrite. Thelatter will thenbe treated by washing as above described and the melted crystal residue, high in .MgCI will be concentrated toslurry and flaked. The wash water in which the ratio is less than will then betreated melted crystal residue for. concentrating to a slurry and flaking.

by melting said crystal mass and concentratat atmospheric pressure, preferably, as described. The tachydrite mother liquor and the wash water from the tachydrite crystals .In thismanner such parent solutions may w be reduced to two. portions, one high in sufficiently. high to permit flaking a slurry derived therefrom, such-separation into two portions being, of course, restricted to those 4 which will not satisfactorily flake as a slurry rectly, provided, the solidification temperature exhibited by a slurry derived therefrom intermediate solution composition ratios is suchias to enable cooling to that temperature withavailable cooling means, and indi- ,.rectly, v after preliminary parting into two portions as described.

,Where natural or other brines are worked for, CaCl rand MgCl by fractional recryst'allization methods involving the precipitation of tachydrite crystals, amother liquor is normally obtained in which the ratio of ranges; between -and a mother liquor supplying a parent 1 admirably adapted toworking by the herein disclosed method.

For example, if'it be desired to produce a mixed flaked magnesium chloride-calcium chloride product containing thechlorides in the ratio of from 6 to 10 parts of the former to 100 of the latter, a saturated solution of o c said chlorides is concentrated at atmospheric pressure to form a slurry of crystals of QCaCl MgCl GI-I O and a mother, liquor nearly'free of magnesium chloride (if desired). Such mother liquor will have a high solidificationtemperature and the hot slurry of the said crystals and mother liquor will be still sufiiciently fluid to behandled readily to in preparing such solution for solidification and forming into particles by any other method of procedure involving cooling and division. Such preparation secures the advantages of high and sharp solidification temperatures.

The flaked form of product has been found to be a very desirable formin which to market hygroscopic chlorides, and my invention accordingly constitutes a valuable advance in the artof flaking mixed hygroscopic chlorides, permitting for the first time the pro-.1

duction of mixed chlorides inthe form of flakes in a cheap and satisfactory manner.

those explained, change being madeas regards the methods employed,. providedthe step or steps stated by any of the following claims'or the equivalent of such stated step or steps be employed. p

' I thereforeparticularly point out and tinctly claim as my invention l 1. In amethod of producingflaked solid mixed chlorides of calcium and magnesium from a solution thereof, the step which consists in concentrating such solution to-form therefrom a slurry ofchloride crystals and mother liquor thereof.

'2. In a methodof producing flaked solid mixed chlorides of calcium andmagnesium from a solution thereof, the steps which conv sist in concentrating suchisolution to form therefrom a slurry of chloride crystals and mother liquor 'thereof,:a'nd then cooling said slurryon a 'flaker to complete solidification.

I In a method of'producing flaked solidmixed chlorides of calcium and magnesium from a solution thereof, the stepswhich cone sist in concentrating such solution to form' therefrom ,aislurry of chloride crystals and mother liquor thereof,'removing a portion pable of being of said crystals, concentrating further and then flaking a slurry of said crystals and final mother liquor.

- 4. In a method ofproducing solid mixed hydrated chlorides ofcalcium and magne sium in (ll VljdEClfOID'l, thestepswhich Consist in concentrating a saturated solution thereof to salt out mixed chloride crystals andvform a slurry of such crystals and a motherliquor consisting largely of a solution of'one such chloride and then solidifying the form of discrete-particles.

said slurry in 5. In a method of producing solidmixed hydratedlchlorides of calcium and'magnesiumiin divided form, the steps whichconsist in-concentrating a saturated solution thereof to-salt out mlxed chloride crystals and form .a slurry of such crystals and mother liquor consisting largely of a solution of one such chloride and then'flaking said slurry.

'6.- In a method of "producing solid mixed hydrated chlorides of calcium and magnesium, the steps which consist in concentrating a saturated solution thereof to salt out mixed chloride crystals and form a mother liquor consisting largely of a solution of one such chloride, removing a portion of such crystals, thereby leaving a slurry of the remaining crystals and mother liquor capable of being pumped by usual means, and solidifying such slurry in the form of discrete particles.

7. In a method of producin solid mixed tion of onesuch chloride, removing a portion flaking such slurry.

hydrated chlorides of calcium and magnesium, the steps which consist in concen trating a saturated solution thereof to salt "out mixed chloride crystals and form a mother, liquor consisting largely of a solu- Other modes of; applying-the principle of my invention may be employed instead of Y of such crystals, thereby leaving a slurry of the remaining crystals and mother liquor ca" pumped by usual means,and

8.;The method of preparing mixed drated chlorides of calcium and magnesiun1- in divided form from mixedsolutions of said salts which comprises concentrating the so lution under vreduced pressure to salt out tachydrite crystals, separating such crystals, further concentrating the residual solution at atmospheric pressure to salt out mixed chlo-V ride crystals and form a slurry of such'crystals and a mother liquor consisting substantially of a solution of calcium chloride and solidifying said slurry in the form of discrete no I of preparing mixed hy particles.- 9. The method drated chlorides of calciumand magnesium' in divided form from mixed solutions of said salts which comprises concentrating the so? lution under reduced pressure to. salt out tachydrite crystals, separatingsuc-h crystals,

further concentrating the residual solution at atmospheric pressure to salt out mixed, A

chloride crystals and form a slurry of such crystals and a mother'liquor consisting substantially of a solution of'calcium chloride and flaking said slurry.

10. The method of Workingup the residual liquor resulting from thecrystallization of tachydrite which comprises concentrating the liquor at atmospheric pressure to salt out mixed crystals of calcium chloride and magnesium chloride and form a slurry of such crystals and mother liquor consisting substantially of a solution of calcium' chloride and solidifying said slurry in the form of discrete particles.

11. The method of Working up the residual I liquor resulting from the crystallization of tachydrite which comprises concentrating the liquor at atmospheric pressure to salt out mixed crystals of calcium chloride and magnesium chloride and form a slurry of such crystals and mother liquor consisting sub- 20 stantially of asolution of calcium chloride and flaking said slurry.

Signed by me this 1st day of November,

SHELDON B. HEATH. 

